Isothermal anisotropic magnetoresistance in antiferromagnetic metallic IrMn.

Antiferromagnetic spintronics is an emerging field; antiferromagnets can improve the functionalities of ferromagnets with higher response times, and having the information shielded against external magnetic field. Moreover, a large list of aniferromagnetic semiconductors and metals with Néel temperatures above room temperature exists. In the present manuscript, we persevere in the quest for the limits of how large can anisotropic magnetoresistance be in antiferromagnetic materials with very large spin-orbit coupling. We selected IrMn as a prime example of first-class moment (Mn) and spin-orbit (Ir) combination. Isothermal magnetotransport measurements in an antiferromagnetic-metal(IrMn)/ferromagnetic-insulator thin film bilayer have been performed. The metal/insulator structure with magnetic coupling between both layers allows the measurement of the modulation of the transport properties exclusively in the antiferromagnetic layer. Anisotropic magnetoresistance as large as 0.15% has been found, which is much larger than that for a bare IrMn layer. Interestingly, it has been observed that anisotropic magnetoresistance is strongly influenced by the field cooling conditions, signaling the dependence of the found response on the formation of domains at the magnetic ordering temperature.

The predominance of substrate induced defects in magnetic properties of Sr2FeMoO6 thin films.

A systematic study of epitaxially grown Sr2FeMoO6 thin films on SrTiO3, (LaAlO3)0.3(Sr2AlTaO6)0.7, SrLaAlO4 and MgO single crystal substrates were made. Transmission electron microscopy investigations showed sharp substrate/films interfaces and increased defect concentration with increased lattice mismatch, indicating defect formation such as dislocations, low angle grain boundaries and stacking faults as a strain relaxation mechanism. Large enough compressive mismatch cause the over-relaxation of the lattice parameters through reorganization or interface defects, which was observed as a tensile strain in films with compressive mismatch larger than -1.05%. All the films with compressive mismatch were phase pure and epitaxially textured while signatures of SrMoO4 parasitic particle was found only in the film grown on MgO. No correlation between the antisite disorder and other structural defects or magnetic properties were found. Instead, the saturation magnetization, Curie temperature, magnetic domain rotation etc are higly dependent on the lattice mismatch induced defects, which outshines the possible correlation with B-site ordering.

Aspirin resistance after CABG.

BACKGROUND: Temporary aspirin resistance can occur during the post-CABG period. If the factors causing resistance can be identified, the incidence of early graft occlusions can also be minimized. METHODS: 25 elective CABG cases were enrolled in the study. The platelet count, mean platelet volume, the C-reactive protein level, lipid profile, blood urea nitrogen (BUN), and creatinine levels were identified one day before the operation and on the 1st, 5th and 10th postoperative days. Optical aggregometry was used for the evaluation of aspirin response. The patients were divided into two groups: those with aspirin resistance and those with no aspirin resistance. RESULTS: The rate of postoperative aspirin resistance was found to be 60 %. No significant difference was found when the preoperative and operative data of the two groups were compared. It was found that the rapid changes observed in the postoperative platelet counts and the C-reactive protein levels were similar. CONCLUSION: Aspirin resistance is encountered during the early postoperative period in the majority of patients undergoing CABG. None of the factors studied were found to be causative for resistance formation. Further studies are required to clarify this entity.

Cost-benefit analysis of primary prevention of sudden cardiac death with an implantable cardioverter defibrillator versus amiodarone in Canada.

BACKGROUND: Clinical trials have shown that implantable cardioverter defibrillators are effective in primary prevention of sudden cardiac death (SCD) in patients with high risk profiles. OBJECTIVES: To conduct a cost-benefit assessment of prevention of sudden cardiac death with an implantable cardioverter defibrillator (ICD) vs. amiodarone from the Canadian health-care system perspective. METHODS: A simulation model that estimates the patient's course following an implantation with an ICD or initiation of amiodarone treatment was created. A thousand pairs of patients with identical characteristics in each treatment group, with similar demographic profiles as observed in the Sudden Cardiac Death in Heart Failure Trial (SCD-HeFT) were simulated. Based on the simulated individual patient characteristics, the model estimated the timing of severe arrhythmic events and deaths due to other causes and implemented the consequences at the time of the events. Patients might die at the time of severe arrhythmia (sudden cardiac death) or survive and become secondary prevention cases and be exposed to a higher risk of severe arrhythmia for the following 6 months. The rates of arrhythmia and death due to other causes were assumed to be the same, whereas the cases of fatality from severe arrhythmia differed between treatments. During the course of the simulation, the clinical (i.e., deaths) and economic outcomes were tallied for both treatment groups. All model parameters were obtained from the literature. The primary data source for clinical inputs was the published results of the SCD-HeFT trial which investigated the impact of ICDs on patients' survival in primary prevention of sudden cardiac deaths compared to amiodarone and conventional therapy. The value of a statistical life (CND$ 5.8 million) was obtained from an analysis previously performed by Health Canada. The direct medical costs and monetary value of lives saved were estimated over 5 years. Sensitivity analyses on key parameters were carried out. The most important study limitation was using two different sources to derive the age dependent clinical risks. This issue was resolved by calibrating the derived risks to account for the population differences. RESULTS: The model predicted that the overall mortality would be reduced by 19.1% (7.1% absolute reduction) with ICD compared to amiodarone over 5 years. The incremental benefit with ICD was estimated at CND$526,700 and additional cost at CND$28,300, which translated into a 0.05 cost: benefit ratio--around 1: 20 return of investment. CONCLUSION: In Canada, ICDs are a worthwhile alternative to amiodarone in the primary prevention of sudden cardiac death.

A rare case of low-grade endometrial stromal sarcoma with myxoid differentiation and atypical bizarre cells.

Endometrial stromal sarcoma (ESS) is a rare mesenchymal tumor with characteristic histological appearances, consisting of diffuse infiltrate of small uniform endometrial stromal cells with a multinodular arrangement and distinct vascular pattern. Less common variants of ESS include "mixed endometrial stromal and smooth muscle tumors", "endometrial stromal tumors resembling ovarian sex cord tumors" and "endometrial stromal neoplasms with endometrial glands", and "aggressive endometriosis". Rarely do endometrial stromal tumors have a prominent fibrous or myxoid appearance which causes confusion and possible misdiagnosis as myxoid leiomyosarcoma. In this report we present a very unusual subtype of ESS in a 32-year-old woman. The tumor revealed atypical pleomorphic bizarre cells which were stained positive only with vimentin and CD10 in an abundant myxoid matrix. A low-proliferative rate was established with MIB-1 staining. To our knowledge such appearance has not been previously reported.

Cost-benefit analysis of preventing sudden cardiac deaths with an implantable cardioverter defibrillator versus amiodarone.

OBJECTIVES: To conduct a cost-benefit assessment of prevention of sudden cardiac deaths with an implantable cardioverter defibrillator (ICD) versus amiodarone from the perspective of the health-care systems in the UK and France. METHODS: Course after implantation with an ICD or taking amiodarone was modeled using discrete event simulation; 1000 pairs of identical patients were simulated 100 times for each analysis. Rates of life-threatening arrhythmia and death from other causes were assumed identical, but the case fatality of arrhythmia and hospitalization differ between treatments. Rates were based on published data, primarily from the Sudden Cardiac Death in Heart Failure Trial (SCD-HeFT). Direct medical costs (in 2004 Euros) and lives saved were estimated over 5 years. The monetary value of a life (UK euro2.1 million, France euro2.0 million) was applied to this benefit and examined relative to the net investment required. RESULTS: ICDs decreased deaths during the 5 years from 37.0% to 29.7% at a net cost of euro26,222 to euro20,008 per patient, yielding cost-benefit ratios of 0.17 (UK) and 0.14 (France)-more than a 5 to 1 return on investment. Sensitivity analyses showed ICDs represent value for money whenever a life is valued at least at euro274,000. CONCLUSION: In these European countries where society values a life at more than euro2 million, ICDs are a worthwhile investment compared with amiodarone for primary prevention of sudden cardiac deaths in patients with heart failure.

Inhibition of the renin angiotensin system decreases fibrogenic cytokine expression in tacrolimus nephrotoxicity in rats.

The aim of our study was to investigate the influence of angiotensin-converting enzyme (ACE) inhibition and angiotensin II receptor blockage on the renal function by light microscopic and immunohistochemical findings in a rat model of tacrolimus nephrotoxicity. Thirty-two male Wistar rats were divided into four groups of eight: G1 = control group; G2-G3, G4 = Tacrolimus (Tac) 1 mg/kg/d intraperitoneally (ip); G3 (Tac + Q) = ip Tac and peroral quinapril 10 mg/kg; and G4 (Tac + V) = Tac and valsartan 40 mg/d. Serum blood urea nitrogen (BUN), creatinine, and creatinine clearance were measured before and at the end of the study period. Renal tissues were assessed for light microscopic findings of tacrolimus toxicity. Transforming growth factor-beta, VEGF, PDGF, BMP-7, and interleukin-6 (IL-6) expression were semiquantitatively scored after immunohistochemical staining. At the end of the study period serum BUN and creatinine levels were increased in all groups, but creatinine clearance was not significantly changed between the groups. Afferent arteriolopathy was significantly less pronounced in G3 versus G2 and G4. Interstial fibrosis was significantly less pronounced in G3 and G4 versus G2. TGF-beta, PDGF, and IL-6 expression were significantly increased in G2, G3, and G4 compared to G1, and in G2 compared to G3 and G4. BMP-7 expression was significantly decreased in G2, G3, and G4 compared to G1, whereas the differences between G2, G3, and G4 failed to reach statistical significance. In conclusion, the results of our study suggested that renin angiotensin inhibition down-regulates fibrogenic cytokine expression in rats displaying tacrolimus nephrotoxicity.